Figure 2.

Microlumina Containing Secreted Apical Domain Components Are Transiently Upregulated during Early Phases of Fluid Accumulation

(A) Representative immunofluorescence images of an apically polarized microlumina in an E3.0 embryo.

(B) Frequency of apically polarized microlumina in E3.0 and E3.25 embryos (p < 0.001).

(C) Representative immunofluorescence image of an E3.25 ICM cell containing an apicosome.

(D) Frequency of apicosome occurrence in E3.0 and E3.25 embryos (p < 0.002).

(E) Representative immunofluorescence image of an E3.25 ICM cell in which a subsection of its membrane facing the growing lumen is apically polarized (L-lumen; C-cytoplasm).

(F) Frequency of lumen polarization in E3.0 and E3.25 embryos (p < 0.0001).

(G) Z slice of an RNA-injected E3.0 embryo showing localization of FGF4-mNeonGreen to the membrane domains of a microlumen, representative of N = 7 embryos.

All scale bars, 10 μm. Two-tailed Fisher's exact test ^∗∗∗∗p < 0.0001, ^∗∗∗p < 0.001, ^∗∗p < 0.01

See also Figures S2 and S3; Videos S5 and S6; Table S2.